Crash when doing override completion in front of an attribute

[davidwengier]

Will all credit for discovery to the wonderful @AdmiralSnyder

Seems to only have a visible effect in LSP, but the code is shared so might be hitting exceptions in the background otherwise.

Repro:

public class Goo
{
    override $$

    [Description("a")]
    public string Name { get; set; }
}

As soon as a character is typed at $$ the following exception occurs:

2025-02-13 09:13:19.542 [info] [Error - 9:13:19 AM] [LanguageServerExtensionManager] Microsoft.CodeAnalysis.CSharp.Completion.Providers.OverrideCompletionProvider threw an exception. System.ArgumentException: identifier
   at Microsoft.CodeAnalysis.CSharp.SyntaxFactory.IdentifierName(SyntaxToken identifier) in /_/src/Compilers/CSharp/Portable/Generated/CSharpSyntaxGenerator/CSharpSyntaxGenerator.SourceGenerator/Syntax.xml.Main.Generated.cs:line 2231
   at Microsoft.CodeAnalysis.CSharp.CSharpSyntaxRewriter.VisitIdentifierName(IdentifierNameSyntax node) in /_/src/Compilers/CSharp/Portable/Generated/CSharpSyntaxGenerator/CSharpSyntaxGenerator.SourceGenerator/Syntax.xml.Main.Generated.cs:line 1489
   at Microsoft.CodeAnalysis.CSharp.CSharpSyntaxRewriter.Visit(SyntaxNode node) in /_/src/Compilers/CSharp/Portable/Syntax/CSharpSyntaxRewriter.cs:line 41
   at Microsoft.CodeAnalysis.CSharp.Syntax.SyntaxReplacer.Replacer`1.Visit(SyntaxNode node) in /_/src/Compilers/CSharp/Portable/Syntax/SyntaxReplacer.cs:line 188
   at Microsoft.CodeAnalysis.CSharp.CSharpSyntaxRewriter.VisitArrayType(ArrayTypeSyntax node) in /_/src/Compilers/CSharp/Portable/Generated/CSharpSyntaxGenerator/CSharpSyntaxGenerator.SourceGenerator/Syntax.xml.Main.Generated.cs:line 1507
   at Microsoft.CodeAnalysis.CSharp.CSharpSyntaxRewriter.Visit(SyntaxNode node) in /_/src/Compilers/CSharp/Portable/Syntax/CSharpSyntaxRewriter.cs:line 41
   at Microsoft.CodeAnalysis.CSharp.Syntax.SyntaxReplacer.Replacer`1.Visit(SyntaxNode node) in /_/src/Compilers/CSharp/Portable/Syntax/SyntaxReplacer.cs:line 188
   at Microsoft.CodeAnalysis.CSharp.CSharpSyntaxRewriter.VisitIncompleteMember(IncompleteMemberSyntax node) in /_/src/Compilers/CSharp/Portable/Generated/CSharpSyntaxGenerator/CSharpSyntaxGenerator.SourceGenerator/Syntax.xml.Main.Generated.cs:line 2086
   at Microsoft.CodeAnalysis.CSharp.CSharpSyntaxRewriter.Visit(SyntaxNode node) in /_/src/Compilers/CSharp/Portable/Syntax/CSharpSyntaxRewriter.cs:line 41
   at Microsoft.CodeAnalysis.CSharp.Syntax.SyntaxReplacer.Replacer`1.Visit(SyntaxNode node) in /_/src/Compilers/CSharp/Portable/Syntax/SyntaxReplacer.cs:line 188
   at Microsoft.CodeAnalysis.CSharp.CSharpSyntaxRewriter.VisitListElement[TNode](TNode node) in /_/src/Compilers/CSharp/Portable/Syntax/CSharpSyntaxRewriter.cs:line 168
   at Microsoft.CodeAnalysis.CSharp.CSharpSyntaxRewriter.VisitList[TNode](SyntaxList`1 list) in /_/src/Compilers/CSharp/Portable/Syntax/CSharpSyntaxRewriter.cs:line 141
   at Microsoft.CodeAnalysis.CSharp.CSharpSyntaxRewriter.VisitClassDeclaration(ClassDeclarationSyntax node) in /_/src/Compilers/CSharp/Portable/Generated/CSharpSyntaxGenerator/CSharpSyntaxGenerator.SourceGenerator/Syntax.xml.Main.Generated.cs:line 1978
   at Microsoft.CodeAnalysis.CSharp.CSharpSyntaxRewriter.Visit(SyntaxNode node) in /_/src/Compilers/CSharp/Portable/Syntax/CSharpSyntaxRewriter.cs:line 41
   at Microsoft.CodeAnalysis.CSharp.Syntax.SyntaxReplacer.Replacer`1.Visit(SyntaxNode node) in /_/src/Compilers/CSharp/Portable/Syntax/SyntaxReplacer.cs:line 188
   at Microsoft.CodeAnalysis.CSharp.CSharpSyntaxRewriter.VisitListElement[TNode](TNode node) in /_/src/Compilers/CSharp/Portable/Syntax/CSharpSyntaxRewriter.cs:line 168
   at Microsoft.CodeAnalysis.CSharp.CSharpSyntaxRewriter.VisitList[TNode](SyntaxList`1 list) in /_/src/Compilers/CSharp/Portable/Syntax/CSharpSyntaxRewriter.cs:line 141
   at Microsoft.CodeAnalysis.CSharp.CSharpSyntaxRewriter.VisitCompilationUnit(CompilationUnitSyntax node) in /_/src/Compilers/CSharp/Portable/Generated/CSharpSyntaxGenerator/CSharpSyntaxGenerator.SourceGenerator/Syntax.xml.Main.Generated.cs:line 1939
   at Microsoft.CodeAnalysis.CSharp.CSharpSyntaxRewriter.Visit(SyntaxNode node) in /_/src/Compilers/CSharp/Portable/Syntax/CSharpSyntaxRewriter.cs:line 41
   at Microsoft.CodeAnalysis.CSharp.Syntax.SyntaxReplacer.Replacer`1.Visit(SyntaxNode node) in /_/src/Compilers/CSharp/Portable/Syntax/SyntaxReplacer.cs:line 188
   at Microsoft.CodeAnalysis.CSharp.CSharpSyntaxNode.ReplaceCore[TNode](IEnumerable`1 nodes, Func`3 computeReplacementNode, IEnumerable`1 tokens, Func`3 computeReplacementToken, IEnumerable`1 trivia, Func`3 computeReplacementTrivia) in /_/src/Compilers/CSharp/Portable/Syntax/CSharpSyntaxNode.cs:line 472
   at Microsoft.CodeAnalysis.SyntaxNodeExtensions.ReplaceTokens[TRoot](TRoot root, IEnumerable`1 tokens, Func`3 computeReplacementToken) in /_/src/Compilers/Core/Portable/Syntax/SyntaxNodeExtensions.cs:line 210
   at Microsoft.CodeAnalysis.Completion.Providers.AbstractMemberInsertingCompletionProvider.RemoveDestinationNodeAsync(Document memberContainingDocument, CodeCleanupOptions cleanupOptions, CancellationToken cancellationToken) in /_/src/Features/Core/Portable/Completion/Providers/AbstractMemberInsertingCompletionProvider.cs:line 216
   at Microsoft.CodeAnalysis.Completion.Providers.AbstractMemberInsertingCompletionProvider.DetermineNewDocumentAsync(Document document, CompletionItem completionItem, CancellationToken cancellationToken) in /_/src/Features/Core/Portable/Completion/Providers/AbstractMemberInsertingCompletionProvider.cs:line 130
   at Microsoft.CodeAnalysis.Completion.Providers.AbstractMemberInsertingCompletionProvider.GetChangeAsync(Document document, CompletionItem item, Nullable`1 commitKey, CancellationToken cancellationToken) in /_/src/Features/Core/Portable/Completion/Providers/AbstractMemberInsertingCompletionProvider.cs:line 48
   at Microsoft.CodeAnalysis.Extensions.IExtensionManagerExtensions.PerformFunctionAsync[T](IExtensionManager extensionManager, Object extension, Func`2 function, T defaultValue, CancellationToken cancellationToken)

Causes a yellow bar in VS for Razor files, or if the LSP C# editor is turned on:

VS Code logs the error:

[JoeRobich]

Ignore me. I should have read more completely.

[jaredpar]

@jasonmalinowski, @jcouv

This seems like an input validation problem at the core. It's an illegal identifier and we're throwing on that. Where is the responsibility for handling illegal input like this between our two layers here?

[jasonmalinowski]

@jaredpar It's not obvious to me what is happening here. If it's hitting this line:

roslyn/src/Compilers/CSharp/Portable/Generated/CSharpSyntaxGenerator/CSharpSyntaxGenerator.SourceGenerator/Syntax.xml.Main.Generated.cs

Line 2231 in 36036f8

default: throw new ArgumentException(nameof(identifier));

is that because we're passing some other token type? I'm OK with that being our fault. I do wish the ArgumentException there included what the unexpected kind was...

[CyrusNajmabadi]

This is very likely an issue on the ide side